Temporary whitelist several cases of disk I/O on the UI threads in cros.

chrome/common/logging_chrome.cc

Index: chrome/common/logging_chrome.cc
diff --git a/chrome/common/logging_chrome.cc b/chrome/common/logging_chrome.cc
index 9653c4071ba03e8762eac32a5e4628bd65cbd094..5ea8012317bb99d6774eb34103c28c503c6c837d 100644
--- a/chrome/common/logging_chrome.cc
+++ b/chrome/common/logging_chrome.cc
@@ -40,6 +40,7 @@
 #include "base/path_service.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
+#include "base/threading/thread_restrictions.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/common/chrome_paths.h"
@@ -213,6 +214,9 @@ void RedirectChromeLogging(const CommandLine& command_line) {
   // defaults to the profile dir.
   FilePath log_path = GetSessionLogFile(command_line);
 
+  // Creating symlink causes us to do blocking IO on UI thread.
+  // Temporarily allow it until we fix http://crbug.com/61143
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
   // Always force a new symlink when redirecting.
   FilePath target_path = SetUpSymlinkIfNeeded(log_path, true);